Field
Embodiments of the present disclosure generally relate to a lightweight thermoplastic/fiber structure for transmitting shear and maintaining the shape of fairings for wings and rotor blade structures.
Description of the Related Art
To maintain stability, torsionally soft structures such as long, slender wings and rotor blades should have a center of gravity in the forward quarter of the blade chord. Fairings are typically formed from skins and a core ‘sandwich’ structure. Composite materials that use thermoplastic, melt-bondable resins provide the possibility of more easily manufactured and tougher structures. Back pressure is needed when forming thermoplastic skins to create a high quality surface and to provide good adhesion of parts of assemblies.
Existing solutions utilize ribs, honeycomb structures, or foam as the core material for fairing structures. Honeycomb structures are often used in rotor blades, however, honeycomb is difficult to melt bond to thermoplastic skins as it does not provide sufficient back pressure over the open portion of the honeycomb cells. Honeycomb structures also pose problems when using soluble tooling. In particular, honeycomb structures do not provide a sufficiently open structure to wash out the soluble tooling medium, even when using a breathable honeycomb structure. Ribs may also be used to form fairing structures. However, ribs must be spaced sufficiently far apart so as not to add too much additional weight. The increased spacing between ribs requires additional stiffening components and thicker skins, which add undesirable weight.